This invention relates to an improvement in a cylinder block of an internal combustion engine to decrease emission of engine noise and to achieve reduction in weight of the cylinder block.
Most cylinder blocks of conventional internal combustion engines are integrally formed with a skirt section located at the lower part thereof. The skirt section is usually secured connected to an oil pan and defines thereinside a crankcase. Although this skirt section contributes to an increase in rigidity of the cylinder block, the skirt section itself vibrates considerably due to vibration resulting from combustion in the engine cylinders, thereby producing considerable noise from the skirt section surface. In other words, the skirt section serves as a secondary noise source.